U.S. patent number 11,433,325 [Application Number 16/560,364] was granted by the patent office on 2022-09-06 for filter element and filter module comprising same.
This patent grant is currently assigned to Pall Corporation. The grantee listed for this patent is PALL CORPORATION. Invention is credited to Ralph Heusslein, Georg Schnieder, Gerhard Strohm.
United States Patent |
11,433,325 |
Strohm , et al. |
September 6, 2022 |
Filter element and filter module comprising same
Abstract
The invention relates to a filter element comprising one or more
fluid-pervious layers of a fluid-pervious sheet material having
first and second surfaces in a substantially parallel arrangement,
a fluid-impervious layer arranged in fluid tight contact with at
least one of said first and second surfaces of said layer(s) of
fluid-pervious sheet material to substantially fully cover the
first and/or second surfaces thereof, one or more first and second
edge portions, said first and second edge portions being arranged
at a predefined distance and separated from one another by a
predefined area of the fluid-pervious sheet material, a fluid flow
path limited to and extending essentially parallel to the first and
second surfaces from the first edge portion(s) to the second edge
portion(s) within each of said layers of fluid-pervious sheet
material, said first and second edge portions providing a fluid
intake and a fluid drainage at the upstream and downstream ends of
said fluid flow path, respectively. The invention further relates
to filter modules comprising one or more of said filter
elements.
Inventors: |
Strohm; Gerhard (Dexheim,
DE), Schnieder; Georg (Bad Kreuznach, DE),
Heusslein; Ralph (Steinbach, DE) |
Applicant: |
Name |
City |
State |
Country |
Type |
PALL CORPORATION |
Port Washington |
NY |
US |
|
|
Assignee: |
Pall Corporation (Port
Washington, NY)
|
Family
ID: |
1000006542959 |
Appl.
No.: |
16/560,364 |
Filed: |
September 4, 2019 |
Prior Publication Data
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Document
Identifier |
Publication Date |
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US 20200078712 A1 |
Mar 12, 2020 |
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Foreign Application Priority Data
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Sep 6, 2018 [EP] |
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18193047 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
B01D
39/1607 (20130101); B01D 29/48 (20130101); B01D
29/46 (20130101); B01D 2201/182 (20130101); B01D
2239/04 (20130101) |
Current International
Class: |
B01D
29/46 (20060101); B01D 39/16 (20060101); B01D
29/48 (20060101) |
Field of
Search: |
;210/435,490,488,253,491,505,508 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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8713306 |
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Nov 1987 |
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DE |
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3093054 |
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Nov 2016 |
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EP |
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3093054 |
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Nov 2016 |
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EP |
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532585 |
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Jan 1941 |
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GB |
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WO 1998/035740 |
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Aug 1998 |
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WO |
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WO 2003/041829 |
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May 2003 |
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WO |
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WO 2008/098689 |
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Aug 2008 |
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WO |
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Other References
European Patent Office, Extended European Search Report in
counterpart European Application No. 18193047.0, dated Mar. 19,
2019. cited by applicant.
|
Primary Examiner: Gonzalez; Madeline
Attorney, Agent or Firm: Leydig, Voit & Mayer, Ltd.
Claims
The invention claimed is:
1. A filter element comprising one or more fluid-pervious layers of
a fluid-pervious sheet material having first and second surfaces in
a substantially parallel arrangement, the first and second surfaces
each having a surface roughness; a fluid-impervious layer arranged
in fluid tight contact with at least one of said first and second
surfaces of said one or more layers of fluid-pervious sheet
material to fully cover the first and/or second surfaces thereof,
providing a substantially flat leveled surface on the at least one
of said first and second surfaces of said one or more layers of
fluid-pervious sheet material; one or more first and second edge
portions, said one or more first and second edge portions being
arranged at a predefined distance and separated from one another by
a predefined area of the fluid-pervious sheet material, a fluid
flow path having an upstream end and a downstream end, the fluid
flow path limited to and extending essentially parallel to the
first and second surfaces from the one or more first edge
portion(s) to the one or more second edge portion(s) within each of
said one or more layers of fluid-pervious sheet material, wherein
fluid flow along the fluid flow path is exclusively limited to flow
within each of said one or more layers of fluid-pervious sheet
material; said one or more first and one or more second edge
portions providing a fluid intake and a fluid drainage at the
upstream and downstream ends of said fluid flow path,
respectively.
2. The filter element of claim 1, wherein the one or more
fluid-impervious layers are materially bonded to the at least one
of the first and second surfaces of the fluid-pervious sheet
material in a fluid tight manner.
3. The filter element of claim 1, wherein said one or more
fluid-impervious layers are in the form of a film.
4. The filter element of claim 1, wherein said one or more
fluid-impervious layers are laminated onto the first and/or the
second surface of the one or more layers of fluid-pervious sheet
material.
5. The filter element of claim 1, wherein said one or more
fluid-impervious layers are bonded to the first and/or second
surface of the one or more layers of fluid-pervious sheet material
under vacuum conditions.
6. The filter element of claim 1, wherein said one or more
fluid-impervious layers have been created in situ on the first
and/or second surface of the fluid-pervious sheet material.
7. The filter element of claim 1, wherein said one or more
fluid-impervious layers are made of a thermoplastic polymer
material.
8. The filter element of claim 1, wherein said one or more
fluid-impervious layers arranged in between two adjacent layers of
fluid-pervious sheet material have a thickness about equal to or
larger than the surface roughness of the first and second surfaces
of the fluid-pervious sheet material.
9. The filter element of claim 1, wherein said fluid-pervious sheet
material is a fibrous depth filter material.
10. The filter element of claim 1, wherein said fluid-pervious
sheet material comprises one or more additives.
11. The filter element of claim 1, wherein a first fluid-impervious
layer is arranged on the first surface of the layer of
fluid-pervious sheet material and a second fluid-impervious layer
is arranged on the second surface of the fluid-pervious sheet
material.
12. The filter element of claim 1, wherein said one or more
fluid-impervious layers are bonded to the layer(s) of
fluid-pervious sheet material with a bonding strength equal to or
larger than a peeling strength of the fluid-pervious sheet material
in a direction perpendicular to the first and second surfaces of
the fluid-pervious sheet material.
13. A filter module comprising one or more filter elements
according to claim 1, said filter module having a fluid inlet
arranged in fluid communication with the fluid intake(s) of the
filter element(s) and a fluid outlet in fluid communication with
the fluid drainage(s) of the filter element(s).
14. The filter module of claim 13, wherein said filter module
further comprises two or more of the filter elements arranged in a
stack such that said one or more first edge portions of each layer
are provided in fluid communication with each other and said one or
more second edge portions are provided in fluid communication with
each other.
15. The filter module of claim 13, wherein the module comprises on
the top and/or on the bottom of the stack a fluid impervious layer
in the form of a first and a second end plate, respectively.
16. The filter module of claim 15, wherein said first and second
end plates are designed as fluid distribution and fluid collecting
devices and comprise a hollow chamber and have an inner rim around
a central opening and an outer rim at the outer periphery, one of
said rims comprising a plurality of openings providing a fluid
communication to and from the hollow chamber in the interior of the
end plate whereas the other rim being closed to seal off said
hollow chamber to the environment.
17. The filter module of claim 15, wherein said first and second
end plates are designed as fluid distribution and fluid collecting
devices and one of them having an inner rim around a central
opening and the other one an outer rim at the outer periphery, said
rims extending from the end plates in a direction away from the
respective surface fluid tightly contacting the stack of filter
elements.
18. The filter module of claim 13, wherein the sheet material of
the one or more filter elements is provided wound around a winding
axis in multiple windings to form a spiral roll with an outer and
an inner peripheral surface, said inner peripheral surface defining
a central channel of the spiral roll, wherein the sheet material is
provided with a first set of through-holes defining the first edge
portions and being arranged such that they form one or more first
channels extending radially in said spiral roll and wherein the
sheet material is further provided with a second set of
through-holes defining the second edge portions and being arranged
such that they form one or more second channels extending radially
and spaced apart from the first channels, said first or said second
channels being open at the outer peripheral surface of the spiral
roll and closed at the inner peripheral surface of the spiral roll;
and said other of said first and said second channels being closed
at the outer peripheral surface of the spiral roll and open at the
inner peripheral surface of the spiral roll.
19. The filter module of claim 18, wherein the filter module
comprises a first and/or a second end plate attached to the top and
bottom front end of the spiral roll, respectively.
20. A filter system comprising a housing and one or more filter
modules of claim 13, said housing comprising an inlet opening in
fluid communication with the fluid inlet(s) of the filter module(s)
and an outlet opening fluidly isolated from the fluid inlet opening
and in fluid communication with the fluid outlet(s) of the filter
module(s).
21. The filter element of claim 7, wherein said thermoplastic
material is selected from polyolefin, polyester and polyamide.
22. The filter element of claim 10, wherein said one or more
additives are comprised in the fluid-pervious sheet material in an
amount of about 80% by weight of the fluid-pervious sheet material
or less.
23. The filter element of claim 12, wherein the one or more
fluid-impervious layers bonded to the first and second surfaces of
one of the layers of fluid-pervious sheet material are bonded to
one another by a plurality of bonding elements extending from one
of the fluid-impervious layers through the layer of fluid-pervious
sheet material to the other one of the fluid-impervious layers,
said bonding elements being essentially regularly distributed over
the area of the layer of fluid-pervious sheet material.
24. The filter element of claim 23, wherein the cross-sectional
areas of the bonding elements in a plane parallel to the surface of
the fluid-pervious sheet material sum up to about 10% or less of
the surface area of the layer of fluid-pervious sheet material.
25. The filter module of claim 14, wherein the filter elements in
the stack comprise a fluid-impervious layer only on the first
surface of the fluid-pervious sheet material and the second surface
of the fluid-pervious sheet material is bonded in a fluid tight
manner to the fluid-impervious layer of an adjacent filter
element.
26. The filter module of claim 15, wherein said first end plate is
designed as a fluid distribution device providing a fluid flow path
from the fluid inlet of the module to the fluid intake(s) of the
filter elements and/or said second end plate is designed as a fluid
collecting device providing a fluid flow path from the fluid
drainage(s) of the filter elements to the fluid outlet of the
module, wherein in case an endplate is provided on the top and on
the bottom of the stack, one of the end plates is in the form of a
fluid distribution device and the other end plate is in the form of
a fluid collecting device.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
This patent application claims the benefit under 35 USC 119(b) of
European Patent Application No. 18193047.0, filed Sep. 6, 2018,
which is incorporated by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a filter element and a filter
module comprising one or more of such filter elements. The
invention further relates to a method for making the inventive
filter elements.
Filter elements comprising porous depth filter material are
abundantly known. The depth filter material is provided in many
cases in the form of a sheet material. The fluid to be filtered is
directed to an upstream surface of the sheet material whereas a
filtrate is drained from the opposite or downstream surface of the
sheet material. The edges of the sheet material are typically
compressed or otherwise sealed in order to pass the fluid to be
filtered in an essentially perpendicular direction to the surfaces
through the sheet material and prevent leakage of fluid at the
edges thereof.
More recently, filter elements using the depth filter material in a
so-called edge-flow arrangement are known from WO 98/35740 A1 where
the fluid to be filtered is directed to first edge surfaces of
stacked circular sheets of depth filter material and the fluid flow
occurs within the depth filter material essentially in parallel to
the surfaces of the individual sheets. The filtrate exits the depth
filter material at second edge surfaces spaced apart from the first
edge surfaces.
Furthermore, as an alternative to the use of stacked circular sheet
material, U.S. Pat. No. 8,464,877 B2 to Diemer et al. proposes an
edge-flow arrangement where a sheet material is wound to form a
spiral roll. The sheet material is provided with multiple openings
the boundary surfaces of which serve as flow-through surfaces. The
openings of the sheet material in subsequent layers of the spiral
roll are positioned on top of one another, thus forming a plurality
of radially extending channels, one group of channels serving as
inlet channels and another group of channels serving as outlet
channels.
While filter elements of this type are useful in various
applications, especially in the field of food and beverage, with
respect to filtration applications, e.g., in the field of
biotechnology and pharmaceuticals, especially where high bacterial
removal efficiencies are of importance, such type filter elements
did not satisfy all requirements.
The object of the present invention is to provide a filter element,
especially for applications where high bacterial removal efficiency
is required.
SUMMARY OF THE INVENTION
The above object is solved by a filter element according to claim
1. The fluids to be treated are typically liquids but may also be
gaseous.
According to the basic concept of the present invention, the filter
element comprises one or more layers of a fluid-pervious sheet
material having first and second surfaces in a substantially
parallel arrangement. A fluid-impervious layer is arranged in fluid
tight contact to at least one of said first and second surfaces of
said layer of fluid-pervious sheet material to substantially fully
cover the first and/or second surfaces thereof. The filter element
further comprises one or more first and second edge portions, said
first and second edge portions being arranged at a predefined
distance and separated from one another by a predefined area of the
fluid-pervious sheet material. Thereby a defined fluid flow path
limited to and extending essentially parallel to the first and
second surfaces of each of said layers of fluid-pervious sheet
material from the first edge portion(s) to the second edge
portion(s) is provided. Said first and second edge portion(s) of
the layer(s) provide a fluid intake and a fluid drainage at the
upstream and downstream ends of said fluid flow path, respectively.
The fluid-pervious sheet material is typically designed as a depth
filter material.
Surprisingly, the filter element of the present invention is
especially suitable for applications where liquids are treated and
high bacterial removal rates are to be obtained. Furthermore, the
inventive filter element allows to restrict the fluid flow path to
extend solely within the volume provided by the individual layer(s)
of fluid-pervious sheet material, thus providing an improved
removal efficiency, especially also in cases where a predefined
removal rate of bacterial contaminants has to be guaranteed.
In a simple embodiment the filter element may have only one first
or one second edge portion. The number of the corresponding second
and first edge portions, respectively, may vary. In one embodiment
there may be only one first and one second edge portion and the
edge portions may be arranged concentrically and the filter element
may be in the form of a hollow cylinder.
In case a single layer of a fluid-pervious sheet material is used
in an inventive filter element both surfaces of the sheet material
are provided with fluid-impervious layers.
In case of filter elements according to the present invention where
multiple layers of the fluid-pervious sheet material are stacked on
top of one another or are wound to a spiral roll, a single layer of
fluid-impervious material may be used to cover the first surface of
a first layer of fluid-pervious sheet material and the second
surface of an adjacent layer of fluid-pervious sheet material.
Thus, the stack or spiral roll can be assembled in different
ways.
According to a first embodiment the multiple layers of
fluid-pervious sheet material are provided with the
fluid-impervious layer only on one surface thereof and only an end
surface (top or bottom) of the stack or (inner or outer surface) of
the spiral roll of fluid-pervious sheet material is provided with a
further fluid-impervious layer.
In another embodiment the layers of fluid-pervious sheet material
of the stack may alternatingly be provided with a fluid-impervious
layer on both surfaces and with no fluid-impervious layers,
provided that both on top and on the bottom (end surfaces) of the
stack is completed with a further fluid-impervious layer.
In addition, it is noted that the fluid-impervious layers need not
to be applied in a fluid tight manner onto the surfaces of the
individual layers before assembling the same to a stack. Thus,
according to one embodiment an alternating assembly of
fluid-impervious layers and fluid-pervious layers may be provided
in the form of a stack, whereas the fluid tight contact of the
fluid-impervious layers to the surfaces of the fluid-pervious
layers is only subsequently established once the stack has been
assembled.
Advantageously, according to the present invention, the
fluid-pervious sheet material may be selected from a broad variety
of fluid-pervious materials and need not be resilient in order to
provide a sealing contact of adjacent layers or stacked filter
elements, since the fluid tight contact is provided by the use of
the fluid-impervious layer(s).
Furthermore, the present invention does not require flat surfaces
of the fluid-pervious sheet material but one or both of the
surfaces may have an irregular structure. Due to the application of
a fluid-impervious layer on one or both surfaces of the
fluid-pervious sheet material in fluid tight contact, reliable
results upon filtration are nevertheless provided.
The present invention further relates to a filter module comprising
one or more filter elements.
Said filter module has a fluid inlet arranged in fluid
communication with the fluid intake of the filter element(s) and a
fluid outlet in fluid communication with the drainage of the filter
element(s).
The filter modules may be incorporated into a filter system.
A still further aspect of the present invention resides in a method
for preparing the inventive filter elements.
DETAILED DESCRIPTION OF THE INVENTION
In accordance with the present invention, the fluid-pervious sheet
material may be made of a fibrous depth filter material.
Alternatively, fluid-pervious sheet material made of sintered
particles, especially ceramic particles, may be used. Furthermore,
open-porous membranes may be used as fluid-pervious sheet
material.
Typical examples of fibrous depth filter materials useful in the
present invention are described in the U.S. Pat. No. 4,676,904 A to
Schroder and in the German utility model registration DE 87 13 306
U1 both of which are incorporated herein by reference in their
entirety.
Fibrous depth filter materials may incorporate natural fibers
and/or polymer fibers, more specifically cellulosic fibers and
polyethylene or polypropylene fibers, respectively. In addition,
so-called step-index fibers may be used, wherein preferably the
core portion is made of a polypropylene based polymer material and
the outer layer is made of a polyethylene based polymer
material.
The fluid-impervious layers may typically be provided as films made
of a polymer material, especially a thermoplastic polymer material.
Also, multilayered films may be used. Preferred multilayered films
comprise a core layer which may be made, e.g., of a polypropylene
based material and cover layers which may be made, e.g., of a
polyethylene based material. The multilayered films may be
prefabricated or assembled from, e.g., three, individual films upon
demand.
In a preferred embodiment of the inventive filter element, the
fluid-impervious layers not only abut and contact the surfaces but
are materially bonded to the surfaces of the fluid-pervious sheet
material in a fluid tight manner.
Bonding of the fluid-impervious layers in the form of a sheet
material to the surfaces of the fluid-pervious sheet material may
preferably be effected by laminating said fluid-impervious layer(s)
onto the first and/or the second surface of the layer(s) of
fluid-pervious sheet material.
The fluid-impervious layers may be provided according to one
embodiment of the invention in the form of a prefabricated
film.
In an alternative embodiment, the fluid-impervious layer is
extruded onto the surface(s) of the fluid-pervious sheet material
in the form of a film.
Preferably, the fluid-impervious layers are laminated to the first
and/or second surface(s) of the layer(s) of fluid-pervious sheet
material.
According to a further preferred embodiment, the fluid-impervious
layer(s) may be bonded to the first and/or second surfaces of the
layer of fluid-pervious sheet material under vacuum conditions.
In a further alternative embodiment of the invention, the
fluid-impervious layer may be created in situ from particulate
components, e.g., in fiber or granular form, which may be directly
applied onto the surface(s) of the fluid-pervious sheet material
and then processed to form the fluid-impervious layer(s) which
fluid tightly contact(s) the surface(s) of the fluid-pervious sheet
material.
Advantageously, the fluid-impervious layer(s) are made of a polymer
material, preferably a thermoplastic polymer material, said
thermoplastic polymer material being selected from polyolefin,
especially polyethylene or polypropylene, as well as polyester and
polyamide.
The layer of fluid-pervious sheet material may be selected from a
variety of sheet materials. It is preferably selected from depth
filter materials, e.g., in the form of a fibrous structure. Such
fibrous structure preferably comprises fibers selected from
cellulosic and polymer fibers or blends of the same. Preferred
polymer fibers are thermoplastic fibers, especially polyolefin
fibers. Preferable fluid-pervious sheet materials of this type are
disclosed, e.g., in the U.S. Pat. No. 4,676,904 A to Schroder and
the German utility model registration DE 87 13 306 U1 as mentioned
above.
According to a further aspect of the present invention the
fluid-pervious sheet material may comprise polymeric fibers which
are compatible with the material the fluid-impervious layers are
made of, thus facilitating and enhancing the bond of the
fluid-impervious layer to the surface(s) of the layer of
fluid-pervious sheet material.
Said fluid-pervious sheet material providing the fluid-pervious
layer(s) may further comprise one or more additives, especially
selected from organic and/or inorganic materials in fibrous, needle
and granular form.
Preferred additives may be selected from kieselguhr, perlite,
polyvinylpyrrolidone (PVPP) and silica gel, preferably in
particulate form, and preferably bonded to the matrix of the
surrounding fluid-pervious sheet material by a resin compatible
with the further components of the fluid-pervious layer.
The amount of said one or more additives is preferably limited to
about 80% by weight or less, based on the weight of the
fluid-pervious sheet material.
According to a still further preferred embodiment, the
fluid-impervious layer(s) arranged in between two adjacent layers
of fluid-pervious sheet material have a thickness about equal to or
larger than the surface roughness or surface irregularities of the
fluid-pervious sheet material. Thus, a fluid tight contact to the
surfaces of two adjacent layers of fluid-pervious material may be
facilitated.
In order to improve the mechanical stability of the inventive
filter elements the fluid-impervious layers arranged on opposite
surfaces of the fluid-pervious sheet material are preferably made
from compatible, more preferably from the same material.
In an especially preferred embodiment, the fluid-impervious layers
on the opposite surfaces of the fluid-pervious layer are bonded to
one another across the body of the layer of fluid-pervious sheet
material, preferably by, e.g., needle shaped, microscopic
bonds.
Such bonds can be easily created by providing a plurality of
microscopic openings, e.g., in the form of pinholes or narrow
slots, extending from one surface of the fluid-pervious sheet
material to the other surface allowing the polymer material
constituting the fluid-impervious layers to penetrate the body of
the fluid-pervious layer and establish a plurality of bonds or
bonding elements between the fluid-impervious layers on the
opposite surfaces. These bonds enhance the mechanical stability of
the individual layer as well as of the filter element as a whole.
The penetrating of the polymer material upon forming the bonds is
greatly facilitated when the fluid-pervious sheet material is
provided in a dry condition.
Typically, the plurality of bonding elements extending from one of
the fluid-impervious layers through the layer of fluid-pervious
sheet material to the other one of the fluid-impervious layers are
regularly distributed over the area of the layer of fluid-pervious
sheet material.
According to a first aspect, the bonds may be designed with a small
cross-sectional area parallel to the surfaces of the fluid-pervious
sheet material and such that they do not noticeably affect the
fluid flow along the fluid flow path within the body of the layer
of the fluid-pervious sheet material. Preferably, the sum of
cross-sectional areas of the bonds is about 2% to about 10%, more
preferably about 3% to about 7% of the surface area of the
fluid-pervious layer, e.g., about 5% or less.
According to a second aspect, the bonds may be provided along
extended narrow slots and may be used in order to deflect the fluid
flow and, furthermore, substantially extend the fluid flow path
from the first to the second edge portions. Thus, the bonds may
serve to modify and adapt the filtration characteristics of the
filter element while the filtration capacity remains essentially
unaffected.
In a preferred embodiment of the present invention, a first
fluid-impervious layer is arranged at the first surface of the
layer of fluid-pervious sheet material, and a second
fluid-impervious layer is arranged at the second surface of the
fluid-pervious sheet material, said first and second
fluid-impervious layers being preferably made of compatible
materials, especially polymer materials, which, more preferably may
be directly bonded to one another when they are brought in contact
with one another in a stack of filter elements.
Generally, it is preferable if said fluid-impervious layers are
materially bonded to the layer(s) of fluid-pervious sheet material
with a bonding strength equal to or larger than the peeling
strength of the fluid-pervious sheet material in a direction
perpendicular to the surfaces of the fluid-pervious sheet material.
Fibrous fluid sheet materials typically have a wet strength of
about 1 N/mm.sup.2 or less.
According to a further aspect of the present invention filter
modules including one or more of the filter elements according to
the present invention are provided which may be set up in different
ways.
According to one aspect of the present invention, a filter module
comprises two or more of the filter elements arranged in a stack
and directly bonded to one another. More preferably, the layers of
fluid-impervious material provide for the bond(s).
In preferred embodiments of the inventive filter module the filter
elements in the stack comprise a fluid-impervious layer only on the
first surface of the fluid-pervious sheet material and the second
surface of the fluid-pervious sheet material is bonded, especially
in a fluid tight manner, to the fluid-impervious layer of an
adjacent filter element, whereas one of the filter elements on the
bottom or on the top of the stack (constituting an end surface) may
comprise a second fluid-impervious layer bonded to the second
surface of the fluid-pervious sheet material of said filter
element.
As noted above, said first and second edge portions of each layer
may be provided in a concentrical arrangement, i.e., the
fluid-pervious sheet material is provided in the shape of a ring.
Multiple layers stacked on top of one another provide a multilayer
filter element of the module in a hollow cylindrical form.
According to another preferred embodiment, the inventive filter
module comprises the sheet material of the one or more filter
elements wound around a winding axis in multiple windings to form a
spiral roll, preferably wherein adjacent surface areas
(fluid-impervious layers or fluid-pervious and fluid-impervious
layers) of the windings of the filter element(s) are in fluid tight
contact, prefe-rably materially bonded, to one another.
Typically, the filter module according to the present invention
further comprises a housing having an inlet opening in fluid
communication with the inlet(s) of the filter element(s) and an
outlet opening fluidly isolated/separated from the fluid inlet
opening and in fluid communication with the outlet(s) of the filter
element(s).
The inventive filter modules may comprise two or more of the filter
elements arranged in a stack such that said first edge portion(s)
of each layer are provided in fluid communication with each other
and said second edge portions are provided in fluid communication
with each other, preferably the filter elements being directly
bonded to one another, optionally wherein the filter elements in
the stack comprise a fluid-impervious layer only on the first
surface of the fluid-pervious sheet material and the second surface
of the fluid-pervious sheet material is bonded, especially in a
fluid tight manner, to the fluid-impervious layer of an adjacent
filter element, a filter element on the bottom or top of the stack
preferably comprising a second fluid-impervious layer bonded to the
second surface of the fluid-pervious sheet material of said filter
element.
In certain embodiments, the filter module comprises on the top
and/or on the bottom of the stack a fluid impervious layer in the
form of a first and a second end plate, respectively, optionally
said first end plate being designed as a fluid distribution device
providing a fluid flow path from the fluid inlet of the module to
the fluid intake(s) of the filter elements and/or said second end
plate being designed as a fluid collecting device providing a fluid
flow path from the fluid drainage(s) of the filter elements to the
fluid outlet of the module, wherein in case an endplate is provided
on the top and on the bottom of the stack, preferably one of the
end plates is in the form of a fluid distribution device and the
other end plate is in the form of a fluid collecting device.
In addition, in specific embodiments of the filter module said
first and second end plates are designed as fluid distribution and
fluid collecting devices and comprise a hollow chamber and have an
inner rim around a central opening and an outer rim at the outer
periphery, one of said rims comprising a plurality of openings
providing a fluid communication to and from the hollow chamber in
the interior of the end plate whereas the other rim being closed to
seal off said hollow chamber to the environment.
In further specific embodiments, the filter module comprises said
first and second end plates, which are designed as fluid
distribution and fluid collecting devices and one of them having an
inner rim around a central opening and the other one an outer rim
at the outer periphery, said rims extending from the end plates in
a direction away from the respective surface fluid tightly
contacting the stack of filter elements.
According to another embodiment of the inventive filter module, the
sheet material of the one or more filter elements is provided wound
around a winding axis in multiple windings to form a spiral roll
with an outer and an inner peripheral surface, said inner
peripheral surface defining a central channel of the spiral roll,
wherein the sheet material is provided with a first set of
through-holes defining the first edge portions and being arranged
such that they form one or more first channels extending radially
in said spiral roll and wherein the sheet material is further
provided with a second set of through-holes defining the second
edge portions and being arranged such that they form one or more
second channels extending radially and spaced apart from the first
channels, said first or said second channels being open at the
outer peripheral surface of the spiral roll and closed at the inner
peripheral surface of the spiral roll;
and said other of said first and said second channels being closed
at the outer peripheral surface of the spiral roll and open at the
inner peripheral surface of the spiral roll; preferably wherein
adjacent surface areas of subsequent windings of the spiral roll of
the filter element(s) are bonded, especially fluid tightly sealed,
to one another.
Quite often the filter modules comprise a first and/or a second end
plate attached to the top and bottom front end of the spiral roll,
respectively.
The end plates mentioned above in connection with the description
of various embodiments of the present invention may be attached in
a fluid-tight manner to the stack of filter elements or a spiral
roll, preferably by materially bonding same to filter elements or
the spiral roll.
When attached to a stack of filter elements, the end plate--also in
case it serves as a fluid distribution or collecting device--may be
directly bonded to a surface of a layer of fluid-pervious material
without the need to have a fluid-impervious layer arranged in
between.
Generally, the materially bonding may be effected in different
ways, e.g., by the application of a gluing material. Preferably,
the materially bonding is effected by heating a surface of the end
plate designed to abut a filter element or a top or bottom end of a
spiral roll, e.g., by infrared radiation, such that it softens or
superficially melts and subsequently contacting the surface of the
stack or spiral roll with the end plate.
Still, a further aspect of the present invention relates to a
filter system comprising a housing and one or more filter modules
as described above, said housing comprising an inlet opening in
fluid communication with the fluid inlet(s) of the filter module(s)
and an outlet opening fluidly isolated from the fluid inlet opening
and in fluid communication with the fluid outlet(s) of the filter
module(s).
According to still a further aspect of the present invention a
process for manufacturing an inventive filter element is
provided.
The process for manufacturing a filter element according to the
present invention comprises the following steps a fluid-pervious
sheet material is provided, preferably in the form of a coil; a
fluid-impervious layer is provided in fluid tight contact with at
least to the first or the second surface thereof; and the first and
second edge portions are provided at a predefined distance and
separated from one another by a predefined area of the
fluid-pervious sheet material, preferably by punching.
In the process according to the present invention the
fluid-impervious layer is provided according to a first embodiment
as a preferably prefabricated film, preferably in the form of a
coil, or is created according to a further embodiment in situ on
one of the first and second surfaces of the fluid-pervious sheet
material.
A fluid-impervious layer may be fluid tightly or sealingly bonded
to both the first and second surfaces of the fluid-pervious
layer.
The bonding of the fluid-impervious layer to the first and/or
second surface to the fluid-pervious layer may be effected in a
calendering step.
The fluid-pervious sheet material may be provided with a plurality
of small openings in the form through-holes, e.g., pin-holes or
narrow slots, regularly distributed across the surface area of the
layer of fluid-pervious sheet material prior to the application of
the fluid-impervious layer(s), and optionally the fluid-impervious
layers on the first and second surfaces of the fluid-pervious sheet
material may be bonded to one another via said small openings.
The advantages of the present invention and its various aspects
will be discussed in more detail in connection with specific
embodiments according to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a first embodiment of a filter element of the present
invention;
FIG. 2 shows a further embodiment of a filter element of the
present invention;
FIG. 3 shows a prior art filter element for reference;
FIG. 4 shows a further embodiment of the present invention;
FIGS. 5A to 5D show various embodiments of a filter element
according to the present invention;
FIGS. 6A, 6B show two further embodiments of the present
invention;
FIG. 7 shows a first method to produce the inventive filter
elements;
FIG. 8 shows a further embodiment to produce the filter elements of
the present invention;
FIG. 9 shows a further embodiment for manufacturing the filter
elements according to the present invention;
FIG. 10 shows a further embodiment for manufacturing the filter
elements according to the present invention;
FIG. 11 shows an embodiment of an inventive filter module
incorporating an inventive filter element;
FIGS. 11A and 11B show two details of the filter module of FIG.
11;
FIG. 12 shows a further embodiment of an inventive filter module
incorporating an inventive filter element in coiled form;
FIGS. 13A and 13B show a further embodiments of inventive filter
modules based on inventive filter elements in stacked form; and
FIG. 14 shows an embodiment of an inventive filter system
incorporating a filter module of FIG. 11.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a first embodiment of the present invention in the
form of a filter element 10, comprising one layer 12 of a
fluid-pervious sheet material 14, having first and second surfaces
16, 18 in a substantially parallel arrangement. On the first
surface 16 a fluid-impervious layer 20 is attached in fluid tight
contact to substantially fully cover the first surface 16. The
filter element 10 furthermore comprises through-holes 22 and 24,
which provide first and second edge portions, respectively, in a
predefined distance from one another.
When used as a filter element fluid enters the through-hole or
channel 22, migrates through the first edge portion into and within
the body of the fluid-pervious sheet material 14 and exits the
filter element 10 at the second edge portion and through-hole or
channel 24 as indicated by the arrows 26, 27 and 28,
respectively.
Filter elements 10 may be easily assembled to filter modules of
various filter capacities just by stacking the filter elements 10
on top of one another with the through-holes or channels 22, 24
being in fluid communication, e.g., in line. In such an embodiment,
it is preferred that the fluid-impervious layer 20 sealingly, i.e.,
fluid tightly, abuts the second surface 18 of a subsequent filter
element in the stack of the module and furthermore may be bonded to
said surface 18 materially.
At an end surface 18 of such a stack, an additional layer of
fluid-impervious material may be fluid tightly attached, such that
the filter module may be easily handled and incorporated, e.g.,
into a housing, providing a fluid inlet and an outlet and further
functionalities necessary for carrying out a filtration
process.
FIG. 2 shows a more complex filter element 40 according to the
present invention comprising three layers 42, 44 and 46 of
fluid-pervious sheet material 14, each layer being covered on a
first surface 48, 50 and 52 with a fluid-impervious layer 20a, 20b,
20c, respectively. The representation of FIG. 2 shows these three
layers 42, 44, 46 in an exploded representation, whereas in reality
these three layers are arranged in fluid tight contact to one
another, where the fluid-impervious layers 20b and 20c abut a
second surface 49, 51 of the layers 42 and 44, respectively.
In order to facilitate the use of the filter element 40, the end
surface 53 of the stack of layers 42, 44 and 46 may also be covered
by a fluid-impervious layer similar or identical to the layers 20a,
20b, 20c. Again, such layer (not shown) will be attached to the
surface 53 in a fluid tight manner.
In operation, as indicated by an arrow IN fluid to be filtered is
fed to a first series of through-holes 61, 62, 63 forming flow
channels and providing a first edge portion. The fluid then
migrates along the fluid flow paths, indicated by arrows 64, 65, 66
essentially parallel to the first and second surfaces of the layers
42, 44 and 46 to the second edge portions provided by the series of
through-holes 67, 68, 69 (arranged as a flow channel) and exits the
filter element as a whole as indicated by an arrow OUT.
Of course, the non-filtrate fluid may be fed into the aligned
through-holes 61, 62, 63 from both ends of the channel formed in
the filter element 40, i.e., from the top and bottom of the filter
element 40.
Likewise, draining of the filtrate may occur on both sides of the
filter element 40 from the channel provided by the aligned
through-holes 67, 68, 69.
From a comparison of the embodiments of FIGS. 1 and 2 it is readily
apparent that the filtration capacity of the inventive filter
elements may easily be scaled up by stacking a larger multiplicity
of layers as mentioned above already. Due to the fluid tight
contact between adjacent layers, no excessive compression forces
are needed to avoid leakage of fluid and to guarantee reliable
results of the filtration process.
FIG. 3 is provided to illustrate the problems encountered in the
prior art when fluid-pervious sheet materials made of fibrous
materials are used. In reality, such sheet materials are
essentially flat on one of the surfaces only, whereas they show a
substantial irregular structure on the opposite surface. Such
structure is due to the manufacturing process of such fibrous
materials. Similar problems may be encountered with other types of
fluid-pervious sheet materials due to an irregular surface
structure.
When two or more layers 70a, 70b are put together in a multilayer
arrangement 82 as shown in the lower part of FIG. 3 in an attempt
to provide a fluid tight contact of the upper and lower surfaces of
the fluid-pervious sheet material, problems may arise as
exemplarily indicated in portions X and Y. The number and the
extension of the portions X and Y may be reduced by applying a
substantial pressure on the multilayer arrangement 82.
Edge portions 74a/b, 75a/b, 76a/b provide fluid flow channels
allowing fluid to be filtered to enter/exit the body of the
fluid-pervious sheet material. For example, in case channel 75 is
used as an inlet channel the fluid to be filtered may more or less
unhindered, i.e., without migrating through the body of the
fluid-pervious sheet material 70a, 70b, flow to the outlet channel
76, whereas fluid traveling into the direction of outlet channel 74
will at least to some extent have to migrate through the
fluid-pervious sheet material 70a, 70b and be filtered. Thus, the
portions X and Y are causing a leakage of fluid, i.e., irregular
filtration results, which is detrimental to the quality of the
filtrate.
By covering the surfaces of the fluid-pervious sheet material with
a fluid-impervious layer in a fluid tight manner, the present
invention avoids such difficulties as is shown in FIG. 4.
The fluid-impervious layers are typically made of a plastics
material which may be applied to the respective surface of the
fluid-pervious sheet material under conditions which allow
compensating and levelling an irregularly structured surface. Thus,
regular fibrous fluid-pervious sheet materials as they are
abundantly used in other filtration purposes may be used according
to the present invention. The same is true for other types of
fluid-pervious sheet materials, as indicated above.
FIG. 4 shows in the upper part two still separate layers of
fluid-pervious sheet material 70c, 70d, corresponding to the
fluid-pervious sheet material 70a and 70b of FIG. 3.
However, the sheet materials 70c and 70d are covered on their first
surface 78c, 78d in a fluid tight manner by fluid-impervious layers
82c, 82d such that both surfaces now have a substantially flat
levelled structure. This facilitates the assembly of the two layers
into a multilayer arrangement 84 as shown in the lower part of FIG.
4, where fluid entering the through-holes 75c, 75d forming an inlet
channel and providing first edge portions will mandatorily have to
migrate through the body of the layers of fluid-pervious material
70c and 70d, respectively. Thus, at the second edge portions
provided by the through-holes 74c, 74d and 76c and 76d forming
outlet channels, respectively, a homogenous and reliable quality of
the filtrate is obtained.
As indicated in the portions X' and Y', the specifically uneven
portions of the upper surface of the layer 70d have been fully
covered and levelled by the fluid-impervious material of layers
82d, such that the leakages occurring in sections X and Y as shown
in FIG. 3 can be safely avoided without applying excessive
pressure.
FIG. 5 schematically illustrates various embodiments of inventive
filter elements in basic setups.
In FIG. 5A a fluid-pervious layer 100 is combined on one of its
surfaces 102 with a layer of a fluid-impervious material 104
(typically a polymer material) so as to provide a structure as
shown for example in FIG. 1. Upon assembling the fluid-impervious
layer fluid tightly contacts the surface 102 of the fluid-pervious
layer 100. First and second edge portions for fluid feed and
drainage may then be provided in the form of through-holes as shown
in FIG. 1.
Typical layer thicknesses for the fluid-impervious layer 104 are
about 100 .mu.m to about 600 .mu.m and are sufficient to cope with
the surface irregularities of typical fluid-pervious sheet
materials. The thickness of the fluid-pervious sheet material may
vary broadly and may be in the range from about 1 mm to about 10
mm, preferably from about 3 mm to about 5 mm.
In the alternative embodiment according to FIG. 5B, the
fluid-pervious sheet material 100 is covered and fluid tightly
contacted on both of its opposite surfaces 102, 103 by sheets of
104, 106 of fluid-impervious material, e.g., a polymer material.
Again, upon assembly the first and second edge portion may be
created, e.g., in the form of through-holes (not shown).
A modification of the structure of FIG. 5B is shown in FIG. 5C
where the sheet of the fluid-pervious sheet material 100 is
provided with microscopic openings in the form of pin-holes 108
penetrating the fluid-pervious sheet material 100 from its first
surface 102 to its second surface 103.
Thus, when the fluid-impervious layers 104, 106 are subsequently
applied to the surfaces 102, 103 of the fluid-pervious sheet
material 100, by sufficiently heating the material of the
fluid-impervious layers 104, 106 and upon application of an
appropriate pressure, the polymer material of the fluid-impervious
layers 104, 106 may enter and fill the pin-holes 108 and form bonds
between the two layers 104, 106 extending through the openings 108
of the sheet 100. These bonds further stabilize the filter element
mechanically such that it may be easier handled and, furthermore,
provides for a higher pressure resistance of the filter elements as
a whole. Surprisingly, these bonds may be created without detriment
to the fluid-impervious properties of the layers 104, 106 due to
their limited cross-sections parallel and perpendicular to the
surfaces of the sheet 100.
In case the fluid-impervious material is polyethylene with a
melting temperature in the range from about 130.degree. C. to about
150.degree. C. heating the assembled multilayer structure of FIG.
5C to a temperature of about 160.degree. C. is typically sufficient
to have the bonds established via the pin-holes 108. Typically,
entering and penetrating the fluid-pervious sheet material via the
pin-holes is facilitated once the sheet material 100 is in a dry
state.
Through-holes (not shown) may be provided as shown in FIG. 1 to
form the first and second edge portions defining the fluid flow
path(s).
Typically, the pin-holes once filled with the polymer material
providing bonds between the upper and lower fluid-impervious layers
104, 106 will not affect fluid flow within the fluid-pervious sheet
material since their cross-sections as well as the sum of their
cross sections parallel to the surfaces 102, 103 of sheet material
100 may be limited to about 5% of the surface area of the
fluid-pervious sheet material 100 or less.
A further alternative to the structure of the filter element of
FIG. 5C is shown in FIG. 5D, wherein the layer of fluid-pervious
sheet material 100 is provided with an elongate narrow slot 110,
extending from the first surface 102 to the second surface 103 of
the fluid-pervious sheet material 100. The slot 110 may replace the
pin-holes 108 in their function to provide a bond between the upper
and lower fluid-impervious layers 104, 106.
The same measures as described for forming the bonds extending
through the pinholes 108 will be sufficient to have the (polymer)
material of the fluid-impervious material enter the narrow slot 110
and from a bond between the layers 104 and 106 all along the
extension of the narrow slot 119. Again, the mechanical stability
of the filter element is improved.
On both sides of the slot 110, first and second edge portions
(channels 112 and 114) are provided at a predefined distance from
one another.
Due to the arrangement of the two edge portions or channels 112,
114 on opposite sides of the narrow longitudinal slot 110, the
fluid entering the channel 112 and migrating through the body of
fluid-pervious sheet material 100, will have to flow around the
area of the slot 110, filled with polymer material bonding the two
layers 104, 106 together. Thus, the fluid flow path of the fluid
from the first edge portion (channel 112) to the second edge
portion (channel 114) is considerably longer than the mere distance
of the two channels 114, 116. Again, the cross-sectional area of
the bonds extending through the narrow slots 110 may be kept
minimal as compared to the surface area of the sheet material and
is not detrimental to the filtration capacity.
Thus, the filtration characteristics of the filter element may be
modified by simple and economic means and the filtration properties
of the filter elements may be adapted to the respective
application.
The latter aspect discussed in connection with FIG. 5D will be
described in detail in connection with the embodiments shown in
FIG. 6.
In FIG. 6A, a filter element 120 is shown in a top view. The filter
element 120 is provided with a plurality of through-holes 121
arranged in three lines 122, 124 and 126. The filter element 120
may have a layered structure of a fluid-pervious sheet material and
two fluid-impervious layers as exemplarily shown in FIG. 5B.
The individual through-holes of line 124 may provide first edge
portions and serve as a fluid inlet, whereas the line of
through-holes 122 and 126 may provide second edge portions for
draining the filtrate. Thus, a fluid flow may occur from the line
of through-holes 124 in more or less direct and straight paths to
the second edge portions of the lines of through-holes 122 and 126
as indicated by the arrows 128, 129. In case pin-holes are provided
(not shown) to bond the fluid-impervious layers on top and bottom
of the fluid-pervious sheet material together as schematically
shown in FIG. 5C, the fluid flow paths 128 and 129 remain
essentially unaffected.
In FIG. 6B a filter element 140 is shown, where through-holes 141
are positioned within the filter element 140 along lines 142, 144
and 146. The line of through-holes 144 may serve to provide the
first edge portions and the two lines of through-holes 142 and 146
may provide the second edge portions for fluid flow paths through
the fluid-pervious sheet material of the filter element 140. The
filter element may have a layered structure of a fluid-pervious
sheet material and two fluid-impervious layers as exemplarily shown
in FIG. 5B.
In order to modify the filtration characteristics in addition to
mechanically stabilize the filter element 140, the fluid-pervious
sheet material of the filter element 140 has been provided with a
plurality of U-shaped narrow slot arrangements 150a, 150b, 150c,
150d, 150e and 152a, 152b, 152c, 152d, 152e, respectively, arranged
between the lines of through-holes 144 and 142 and between the
lines of through-holes 144 and 146, respectively.
The narrow slots provided between the lines of through-holes 144
and 142 and 146, respectively, are filled with fluid-impervious
material of the fluid-impervious layers once the filter element 140
has been assembled, similar to what has been described in
connection with FIG. 5D. The fluid-impervious material filling the
slots serves as a bond between the fluid-impervious layers on the
top and the bottom of the filter element 140 (not shown) as
indicated in FIG. 5D.
In addition, these bonds influence and direct the fluid flow paths
of the fluid within the fluid-pervious sheet material. When
entering the fluid-pervious sheet material via the first edge
portion provided by the through-holes of line 144 the fluid will
have to migrate to the through-holes of lines 142 and 146,
respectively, following a tortuous path as indicated by the arrows
154, 156 in FIG. 6B in contrast to what is shown in FIG. 6A. The
fluid flow paths in this embodiment of FIG. 6B are about three
times as long as in the embodiment of FIG. 6A.
As mentioned before, the filtration characteristics of the filter
element 140 can thus be modified to a very large degree, although
the general structure of the filter element may remain similar to
the one of filter element of FIG. 5B.
In the following FIGS. 7 to 10, various apparatuses for efficiently
manufacturing the inventive filter elements will be exemplarily
described.
FIG. 7 shows an apparatus 200 in a schematic representation for
manufacturing filter elements according to the present invention
and according to a process for manufacturing the same according to
the present invention.
The apparatus 200 comprises a feed unit 202 for a fluid-pervious
sheet material 204, which is typically provided in the form of a
coil, as shown in FIG. 7. A further feed unit 206 provides a
fluid-impervious layer 208, which is also typically provided in the
form of a coil. Both feed units 202 and 206 provide the sheet
material in a parallel orientation abutting one another, as is
shown at the position 210 in FIG. 7.
Typically the fluid-pervious sheet material 204 may be of a fibrous
structure as described, e.g., in the U.S. Pat. No. 4,676,904 A to
Schroder and having a thickness of, e.g., 3.8 mm. The
fluid-impervious layer 208 is typically provided as a polymer film,
e.g., a polyethylene film of a thickness of 400 .mu.m.
In the feed direction 211 downstream of position 210, a calendar
212 is provided, which serves to bring the two sheet materials 204
and 208 into close contact with one another and preferably heats
the fluid-impervious layer 208 up to an extent that it materially
and fluid tightly bonds to the fluid-pervious sheet material
204.
Downstream of the calender 212, a punching device 214 is provided
for creating through-holes in the double layered material, which
will serve to provide the first and second edge portions in a final
filter element.
Subsequently, the double-layered sheet material 215 is optionally
heated up at position 216 in order to firmly bond the impervious
layer 208 to a surface of the fluid-pervious sheet material 204. In
case the calender 212 has been equipped with a needle-roller (not
shown) creating pin-holes in the fluid-pervious sheet material 204,
the fluid-impervious material of the layer 208 may penetrate into
the microscopic openings or pin-holes provided.
In a final step, the double-layered sheet material 215 is processed
to form filter elements, either by cutting the endless sheet
material 215 into predetermined individual sheets, which are
stacked on top of one another and then assembled to a final
multilayer filter element 220. Alternatively a filter element may
be made by coiling the double-layered sheet material similar to
what is described, e.g., in U.S. Pat. No. 8,464,877 B2 to Diemer et
al. and shown in FIG. 12.
Pin-holes or narrow slots may be provided penetrating the
fluid-pervious sheet material 204, e.g., by an additional equipment
of the calender 212 (not shown). For example, a needle-roller may
be provided as part of the calender 212 as mentioned above or may
be arranged up-stream or down-stream of the calender 212 as a
separate unit.
In a further alternative embodiment, the punching device 214 may
also be used to provide microscopic openings or pin-holes or narrow
slots, which serve to direct part of the molten material of the
fluid-impervious sheet 208 to penetrate the fluid-pervious sheet
material 204 and bond it to a subsequent layer, e.g., when forming
the stack 220.
An alternative apparatus 250 is schematically shown in FIG. 8,
which includes a feed unit 252 for a fluid-pervious sheet material
254, which is typically provided in the form of a coil.
Subsequent to the feed unit 252, a polymer distributor device 256
is provided which may distribute a thin layer 258 of a particulate
material (typically a polymer material), e.g., in fibrous and/or
granular form, on a first surface of the fluid-pervious sheet
material 254, to form a fluid-impervious layer in a subsequent step
in a calender unit 260, where the particulate polymer material is
molten to form a continuous fluid-impervious layer closely
contacting to the fluid-pervious sheet material 254.
Subsequently, as has been described in connection with the
apparatus 200 of FIG. 7 already, a punching device 262 serves to
punch or cut through-holes into the double-layered sheet material,
thus providing for openings forming the first and second edge
portions for the filter elements to be produced.
The heating unit 264 finally provides for an intimate fluid tight
contact and bond between the fluid-impervious layer 259 and the
fluid-pervious sheet material 254.
Subsequently, the endless double-layered material 263 is cut into
shape in order to build the stacked filter element 268.
Again, as noted before, instead of a stack of sheet material a coil
may also be formed in order to serve as a filter element.
Pin-holes or narrow slots may be provided in the fluid-pervious
sheet material by separate units or by integrating further
functions into calender 260 and/or punching device 262 similar to
what has been described in connection with FIG. 7.
In FIG. 9 a further alternative apparatus 300 is schematically
shown, wherein as in the apparatus 200 of FIG. 7 a fluid-pervious
sheet material 304 is provided by a feed unit 302, whereas the
fluid-pervious sheet material 304 is typically in the form of a
coil.
Furthermore, a feed unit 306 provides for the fluid-impervious
layer also in the form of a coiled sheet material 308, which is
arranged in parallel to the fluid-pervious sheet material 304 and
brought in fluid tight contact in calendering unit 310.
Subsequently, the double-layered sheet material 312 is fed into a
punching apparatus 314, which provides for through-holes in the
double-layered material, which provide for the first and second
edge portions of subsequently formed filter elements.
The double-layered material may be cut into the desired shape and
assembled in a stack 320. The stack 320 may then be transferred to
a heating station 324, wherein the stack 320 is compressed and
heated up in order to provide for a close fluid tight contact and
material bonding of the adjacent double-layered sheet
materials.
Pin-holes or narrow slots may be provided in the fluid-pervious
sheet material by separate units or by integrating further
functions into calender 310 and/or punching device 314 similar to
what has been described in connection with FIG. 7. Again, when
forming the stack 320 and compressing and heating the same, the
pin-holes and narrow slots, respectively, will be penetrated by the
material of the fluid-impervious layers and bonds will be formed as
described above.
FIG. 10 shows a further apparatus 350 wherein a feed unit 352
provides fluid-pervious sheet material 354, typically in the form
of a coil.
Upstream of the coiled fluid-pervious sheet material 354, a feed
unit 356 is provided which feeds a fluid-impervious layer 358,
typically from a coil, into the apparatus 350, to abut the upper
surface of the layer of the fluid-pervious sheet material 354.
Downstream of the feed unit 352, a further feed unit 360 is
provided which feeds a fluid-impervious sheet material 362 into the
apparatus 350 so that it abuts the lower surface of the
fluid-pervious sheet material 354.
Thus, downstream of the feed unit 360, a sandwiched structure 366
of a first sheet of fluid-impervious material 358, a fluid-pervious
sheet material 354 and another fluid-impervious material 362 is
provided, which is then passing through a calender unit 370 which
brings the assembled layers into close contact with one another and
especially provides a multilayer material which may be provided in
the downstream punching unit 374 with through-holes forming first
and second edge portions.
Downstream of the punching unit 374, a heating apparatus is
provided with heating units 378, 380 on the upper and lower
surfaces of the multilayer material 366 and the layers 358, 352 and
362 are brought into fluid-tight contact.
In the final unit 384, the multilayer material 366 is cut into
shape in order to provide individual elements to be assembled into
a stacked filter element 386. Otherwise, the multilayer material
366 may be coiled (not shown).
Pin-holes or narrow slots may be provided in the fluid-pervious
sheet material 354 by separate units or by integrating further
functions into calender 370 and/or punching device 374 similar to
what has been described in connection with FIG. 7 already.
Upon forming the stack 386 or optionally already when passing
through the heating units 378, 380 the pin-holes or narrow slots
may be filled with material of the fluid-impervious sheets 358, 362
and form bonds between the fluid-impervious layers contacting the
surfaces of the fluid-pervious layer 354 on top and bottom.
FIG. 11 shows an exemplary embodiment of a filter module 400
according to the present invention. The module 400 comprises two
filter elements 402, 404 which are comprised of a stack of layers
406 of fluid-pervious sheet material. In between the various layers
of fluid-pervious sheet-material 406, layers 408 of
fluid-impervious material are positioned which are in fluid-tight
contact with the respective surfaces of the individual
fluid-pervious layers 406.
The stacks of layers 406, 408 are provided with channels 410, 412
wherein the channels 410 having a larger diameter than the channels
412 and serve as fluid inlet channels for the non-filtrate whereas
the channels 412 serve as drainage channels to receive and drain
the filtrate.
Through-holes in the individual layers 406, 408 are aligned in the
stack configuration of the layers in order provide the continuous
fluid channels 410, 412 in each one of the filter elements 402,
404.
The modules 402, 404 comprise at the respective top ends an end
plate which is designed as a fluid distribution device 420 whereas
at the bottom of the stack a fluid collection plate 422 is
provided. The stacks 402, 404 furthermore are provided with a
central inlet channel 426 which is in fluid communication with an
inlet port 430 of the filter module 400.
The fluid distribution device 420 also comprises a central opening
428 which is preferably of about the same width as the channel 426.
On the surface facing the channel 426, the distribution plate 420
is provided with a number of openings 432 which allow the
nonfiltrate to enter the space within the distribution device 420
as shown especially in detail A (FIG. 11A).
The fluid distribution plate 420 is provided on its lower surface
with openings 434 providing access to the channels 410 of the stack
402.
Thus, the non-filtrate enters the filter module 400 via the inlet
430, flows up within the channel 426 and enters the fluid
distribution plates 420 through the openings 432. Then, the
non-filtrate enters the stacks 402, 404 and their channels 410,
respectively. The fluid then flows in a radial direction through
the stacked layers 406 and is collected as a filtrate in the
drainage channels 412 of the stacks 402, 404.
At the respective bottom of the stacks 402, 404, a filtrate
collecting device 422 is positioned which is also of a disc-shaped
structure, similar to that of the fluid distribution plate 420.
In contrast to the structure of the fluid distribution plate 420,
the volume provided by the fluid collecting plate 422 is sealed off
against the inlet channel 426 whereas on the outer periphery the
fluid collecting plate 422 is provided with a plurality of openings
440 (cf. FIG. 11B) which allow drainage of the filtered fluid from
the channels 412 to the outside of the filter modules 400 where it
may be collected and directed to a fluid outlet (not shown in FIG.
11).
The interior surface of the stacks 402, 404 may be sealed off
against the channel 426 according to one embodiment. However, this
is not necessary for quite a number of applications, but the
interior surface may be used as a further first edge portion which
allows fluid to penetrate the fluid-pervious sheet material 406
directly from the central channel 426 and the filtrate will be
drained through drainage channels 412 within the corresponding
stacks, which are adjacent to the channel 426.
Similarly, the outer surface 444 of the stacks 402, 404 may be
sealed off, but also left uncovered in numerous applications and
allow an amount of filtrate to exit the individual layers of
fluid-pervious material 406 directly to the environment of the
filter module 400. The thickness of the endplates 450 and 452 may
be, e.g., about 6 to about 7 mm.
The filter module 400 is preferably provided on its upper surface,
i.e., on the upper surface of the fluid distribution plate 420,
with a further end plate 450 and at the lower end with a further
bottom plate 452, which further stabilize the mechanical structure
of the individual stacks and makes it easier to handle them when
forming the module 400.
On top of the module 400, a top plate 454 comprising a handle 456
may be provided in order to facilitate handling, e.g., inserting of
the module into a filter housing or vessel and removing same. The
top plate 454 closes the channel 426 at its upper end.
The fluid inlet 430 may be provided with a plate-shaped circular
element 458 which provides further mechanical stability to the
bottom portion of the filter module 400.
It is noted that, while in FIG. 11 the stacks 402, 404 of
fluid-pervious and fluid-impervious sheets 406, 408 each have a top
and a bottom layer 408, such top and bottom layers 408 of each
stack 402, 404 may be avoided and the uppermost and lowermost layer
406 of fluid-pervious material may be directly bonded to the fluid
distribution plate 420 and the filtrate collection plate 422,
respectively.
Also, the fluid distribution plate 420 as well as the fluid
drainage plate 422 may be designed such that they incorporate the
function of the top and bottom plates 450, 452 which will result in
an even more simplified procedure when assembling the filter module
400.
FIG. 12 shows a filter module 500 where a double layer 504 of
fluid-pervious sheet material and a fluid-impervious sheet
material, for example as obtained from the process described in
connection with any one of FIGS. 7, 8 and 9, is wound up into a
coiled form around a cylindrical supporting structure 510 which
defines the inner diameter of a central channel 512 of the filter
module 500. Prior to winding up the double-layered material 504 to
a spiral roll 502, the double-layered sheet material 504 is
provided with slot-type openings 520, 522 in a similar way as it
has been described in the above-referenced U.S. Pat. No. 8,464,877
B2 to Diemer et al. (cf. especially FIGS. 1 and 3). In the coiled
form of spiral roll 502, the slots 520 form channels which are open
at the outer periphery of the spiral roll 502 and closed at the
inner end thereof whereas the slot-type openings 522 form channels
which are open at the inner periphery of the spiral roll 502 and
closed at the outer periphery as is readily apparent from FIG.
12.
Again, fluid entering the filter module 500, e.g., by a fluid inlet
530 at the bottom of the module 500, will flow up in channel 512 to
the top of the filter module 500 which is closed by a top plate 532
which incorporates a handle 534.
While the top plate 532 may extend across the whole diameter of the
spiral roll 502, it may be supported as shown in FIG. 12 by a
separate circular end plate 536 which is structured similarly to a
bottom end plate 538 to which the fluid inlet 530 may be attached.
Thus, the fluid flowing up from the fluid inlet 530 to the top
plate 532 will then be forced to enter into the channels 522 which
in this operational mode serve as inlet channels for the
nonfiltrate, then travel along the longitudinal direction of the
filter module 500 up or down into the adjacently provided outlet
channels 520 where the filtrate then exits the module 500 to the
surrounding space of the spiral roll 502 which is typically limited
by a filter housing (not shown).
The coiling of the inventive filter element, i.e., the spiral roll
502, is much simpler than what is described in the afore-mentioned
U.S. Pat. No. 8,464,877 B2 to Diemer et al. in that the layers
abutting one another may be directly, fluid-tightly bonded to one
another and no additional compressing and/or sealing elements
between the adjacent windings are necessary. Furthermore, the
fluid-tight contact of subsequent layers of the spiral roll 502
ensures that no leakage may occur so that a high quality and high
filtration efficiency may be provided.
It is readily apparent that the mode of operation of the filter
module 500 may be reversed. Fluid to be filtered will then be fed
to the outer periphery of the module 500, enter the channels 520,
migrate through the fluid-pervious material of the layers 504 of
the spiral roll 502 and filtrate may be drained via channels 522 to
the central channel 512. The tubular part 530 (referred to as fluid
inlet in the first mode of operation described above) will then
serve as a fluid outlet of the filter module 500.
FIG. 13A shows a further embodiment of an inventive filter module
550 which is set up by a multiplicity of double layers of
fluid-pervious and fluid-impervious layers as obtained, for
example, in the process as described in connection with anyone of
FIGS. 7 to 10.
The individual double (or triple) layers 552 are provided with
through-holes to form channels 554, 556 which, when assembled to a
stack, extend from the top to the bottom of the stack of layer
material 552.
On top of the stack of layers 552, a top plate 558 is provided
which has throughholes 560 which are placed in line with the
channels 554. At the bottom of the stack of layers 552 and to the
bottom of the stack, a bottom plate 564 is attached which has a
multiplicity of through-holes 566 which are lined up with the
channels 556 of the stack of layers 552.
In addition, the top plate 558 has a central opening 568 surrounded
by a ring-shaped projection 570. The bottom plate has a ring-shaped
projection 572 at the outer periphery corresponding to the outer
periphery of the stack of layers 552 and a central opening 574 the
diameter of which is the same as the diameter of the central
opening 568 of the top end plate 558.
The diameter of the openings 568 and 574 is in addition compatible
with the diameter of an inner channel 576 provided in the center of
the stack of layers 552.
Thus, fluid may be provided from the outer periphery of the filter
module 550 entering into the channels 554 via the through-holes 560
of the top plate 558, migrate through the fluid-pervious sheet
material of the layers 552 and exit the fluid-pervious material of
the layers 552 into the channels 556. From these channels 556, the
fluid may be drained via the openings 566 of the bottom plate.
The module 550 as described in connection with FIG. 13A may be
easily assembled to larger filtering entities as shown in FIG. 13B
where a number of four filter modules 550 are fluid-tightly
connected to one another via the outer projecting rims 572 and
ring-shaped projections 570, respectively.
While the top module 550a is provided with a sealing cap 580
closing the central fluid channel 582, the opening 568 of the
lowermost module 550d is provided with a fluid outlet tube 584.
As indicated in FIG. 13B, fluid may be provided from the outside of
the filter modules 550a to 550d and enter the modules from their
outer periphery as well as through the openings 560 of their end
plates 558 and the filtrate is drained via the channels 556 within
the individual modules, collected in the space provided by the
bottom plate 564 of each module and collected in the central
channels 576. The channels 576 of each one of the modules 550a to
550d are aligned to one continuous channel 582 which allows
draining the filtrate from all of these four modules via one common
outlet 590.
It is again readily apparent from FIGS. 13A and 13B that the fluid
flow for filtering fluid may be reversed such that fluid to be
filtered is fed into channel 576 (or 582). The fluid then is
distributed by the bottom plates 564 into the plurality of channels
566, migrates through the fluid-pervious layers of the double (or
triple) layers 552 to be collected as a filtrate in the channels
554 and exit the module 550 via the openings 560.
For both modes of operation the outer and/or inner peripheral
surfaces of the module 550 may be sealed off or let uncovered and
will in the latter case contribute to filtration capacity.
FIG. 14 shows a filter system 600 comprising a housing 602 which
provides an inner space 604 to accommodate a filter module, e.g., a
filter module 400 as described in detail in connection with the
FIGS. 11, 11A and 11B. The housing 602 is typically provided in a
two-part form with a bottom plate 610 which provides for a fluid
inlet 612 and a fluid outlet 614 and a top portion 616 providing
for the interior space 604 to accommodate the filter module
400.
At the top end of the housing 602, a venting opening 618 may be
provided which allows in the beginning of the operation of the
filter system 600 to vent the air included in the housing to
escape, and once the interior 604 of the housing 602 is filled with
the fluid to be filtered, the opening 618 may be closed.
During filtration operation of the filter system 600, the fluid
enters, e.g., into the fluid inlet 612, flows up into the central
channels 426 of the stacks 402, 404 of the filter module 400, is
distributed into the various channels 410 of the stacks 402, 404
and then exits the filter module 400 via the channels 412 and the
filtrate collecting plates of the module to accumulate in the
interior 604 of the housing 602 to be drained via the fluid outlet
614.
For some embodiments, it may be advantageous to have the upper part
616 of the housing 602 be divided into a lower cylindrical part 620
and a separable top portion 622.
As is easily understood, the operation of the filter system 600 and
the filter module 400 may be reversed such that the tubing 614
serves as a feed inlet and the filtrate is drained via the tubing
612.
The use of the terms "a" and "an" and "the" and "at least one" and
similar referents in the context of describing the invention
(especially in the context of the following claims) are to be
construed to cover both the singular and the plural, unless
otherwise indicated herein or clearly contradicted by context. The
use of the term "at least one" followed by a list of one or more
items (for example, "at least one of A and B") is to be construed
to mean one item selected from the listed items (A or B) or any
combination of two or more of the listed items (A or B), unless
otherwise indicated herein or clearly contradicted by context. The
terms "comprising," "having," "including," and "containing" are to
be construed as open-ended terms (i.e., meaning, "including, but
not limited to,") unless otherwise noted. Recitation of ranges of
values herein are merely intended to serve as a shorthand method of
referring individually to each separate value falling within the
range, unless otherwise indicated herein, and each separate value
is incorporated into the specification as if it were individually
recited herein. All methods described herein can be performed in
any suitable order unless otherwise indicated herein or otherwise
clearly contradicted by context. The use of any and all examples,
or exemplary language (e.g., "such as") provided herein, is
intended merely to better illuminate the invention and does not
pose a limitation on the scope of the invention unless otherwise
claimed. No language in the specification should be construed as
indication any non-claimed element as essential to the practice of
the invention.
Preferred embodiments of this invention are described herein,
including the best mode known to the inventor for carrying out the
invention. Variations of those preferred embodiments may become
apparent to those of ordinary skill in the art upon reading the
foregoing description. The inventors expect skilled artisans to
employ such variations as appropriate, and the inventors intend for
the invention to be practiced otherwise than as specifically
described herein.
* * * * *